One of the variety of conduit fittings conventionally employed in conduit systems includes a "flat-face" seal tube connector. In this connector the fitting body is provided with a flat radial surface end lying in a plane perpendicular to the fitting body axis, and an annular recess is usually defined within the fitting body end intersecting the end surface receiving an elastomeric ring normally slightly axially projecting beyond the plane of the surface. A component to be connected to the "flat-face" connector includes a radial flange which engages the fitting body seal face and elastomeric ring, and connector means, such as a nut, are employed to force the flange against the seal face to establish a fluid tight connection.
Such a fitting connection requires that the tube be accurately flanged so as to be capable of establishing a sealed relationship to the radial fitting surface, and such machining or shaping is expensive and time-consuming.
It is an object of the invention to provide fitting structure permitting a tube to be attached to a flat-face fitting body in a fluid tight relationship without modification to the tube.
A further object of the invention is to provide a tube connector fitting of a flat-face type wherein machining or modification to the tube is not required, and wherein a metal-to-metal sealing engagement exists between the components to assure fluid tight assembly.
Another object of the invention is to provide a flat-face sealed tube connector which eliminates the need for tube modification by employing a ferrule, and the ferrule includes means for achieving a positive "stop" with respect to the assembly nut axial movement to prevent undesirable deforming of the ferrule or tube.
An additional object of the invention is to provide a flat-face sealed tube connector utilizing a ferrule wherein the ferrule includes serrations embedding into an unmodified tube, and an elastomer ring may be employed with the ferrule for further preventing leakage.
In the practice of the invention, a fitting body includes a radial face having an annular recess defined thereon receiving an elastomeric "O" ring having a greater normal axial dimension that the depth of the recess. The fitting body is externally threaded adjacent its end, and the fitting body may be soldered or threaded upon a tube or other conduit system connection, or otherwise permanently affixed to the conduit system.
A ferrule placed upon the end of a metal tube includes a concentric recess for receiving the end of the tube, and a flat radial surface for engaging the fitting body sealing face and "O" ring. A compression nut rotatably mounted upon the tube includes threads for engaging the threads of the fitting body, and also includes an annular conical cam surface for engaging and inwardly deforming an annular sleeve portion formed upon the ferrule. Internally, the ferrule includes serrations which embed into the tube as the nut is tightened, and an elastomeric ring may be located within the ferrule adjacent to the serrations for compression upon the tube as the nut is tightened.
The ferrule head includes a radial abutment surface axially spaced from the ferrule sealing face, and a radial surface defined upon the compression nut engages the ferrule abutment surface upon the nut being threaded to its full extent upon the fitting body. The engagement of the abutment surfaces produces a positive stop which ensures a consistent assembly procedure and prevents extrusion or undesirable deformation of the ferrule or other components. The positive stop engagement of the ferrule and nut immediately informs the operator that the assembly of the fitting is complete.
As the tube end is merely inserted into the ferrule recess, no prior machining or deforming of the tube is required, the tube only needs to be cut to the desired length, and the only modification to the tube end that occurs is the embedding of the ferrule serrations therein during tightening of the nut.